A match where the map time runs out and both teams are at equal points. In competitive pro games, usually followed by an overtime Golden Cap to determine the winner, not on the official Valve ladder where draws cannot happen due to a lack of a map timer.

Good half. Said at the end of the first half of the match as a show of good sportsmanship.

GG

Good game. Said at the end of the match as a show of good sportsmanship.

Ghosting

Usually said about players that use a cheat to follow players through walls. Can also be said of a dead player that gives information about an alive player when the server allows spectating the other team after death.

GLHF

Good Luck, Have Fun. Said at the beginning of the game as a show of good sportsmanship.

Golden Cap

Reached when map time runs out and both teams are at an equal score on 5CP. There is no round timer and the first to cap the enemy's last point is declared the winner.

Griefing

A player that is griefing is intentionally sabotaging/throwing a game for his teammates.

North America. Often used pejoratively to qualify a poor play, for example "an NA push" or "an NA pop". This stems from the term used in Counter-Strike, where North America is notorious for performing poorly overall.

Noob/Newb/Newbie

Designates a new player. Often used pejoratively to say that someone doesn't know how to play.

NS

Nice shot. Used to compliment a nice shot.

NT

Nice try. Used to compliment a nice move or play even though it failed.